1. Field of the Invention
The present invention relates to an exposing apparatus for exposing one sides of works, and more particularly to an exposing apparatus with mask alignment system which comprises an alignment system for aligning a mask film on which an exposing pattern is formed and a method of aligning, exposing and transferring a work.
2. Prior Art
The process of exposing a work with a predetermined exposing pattern of a mask film is generally carried out in different stages: alignment stage and exposing stage. That is, as shown in FIG. 14, locating marks of the work W and mask film M are taken by cameras 68 in the alignment apparatus 67, and the work W is aligned with the mask film M using a monitor 69, an alignment table and others. Thereafter, the aligned work and mask film are stored in storage spaces 66 of a stock-unit 65 and the stock-unit 65 is moved to an exposing apparatus 60 and the work is exposed by the exposing apparatus 60.
In the exposing apparatus 60, a vacuum frame for holding the work W is arranged such that one side of an upper transparent frame plate 61 is pivotally placed at one side of a lower transparent frame plate 62 with a hinge 63 so that the upper transparent frame plate 61 is opened and closed. The upper transparent frame plate 61 is formed in a square shape and comprises an upper transparent plate 61a. The work W and the mask film M are held between both frame plates 61 and 62 by sucking air in the space surrounded by the upper transparent plate 61a and sealing rubber. The work W is transfered to the exposing stage in the exposing apparatus while held between the upper and lower frame plates 61 and 62 and then exposed therein.
Some of the exposing apparatus comprise an alignment system. As shown in FIG. 15, in the exposing apparatus 70, cameras 72 and an alignment table 71 are placed at the lower part in the alignment stage, so that the images of the mask film on the work is taken from the bottom thereof. Therefore, it is required to form holes at predetermined positions in the work W to be exposed.
Further, in the exposing apparatus 70, the upper transparent frame plates 74 are provided so as to reciprocate on respective transfering paths 75 which are provided horizontally from the alignment stage to the exposing stage, and the frame plate 74 is pivotally moved with a fixed rotating part 74a, as shown by imaginary lines. One of the lower frame plates 73 each holding the work W with the upper transparent frame plate 74 is placed in the alignment stage, and the other lower frame plate 73, together with the upper frame plate 61 is placed in the exposing stage.
The mask film is fixed on the respective transparent plate of the upper transparent frame plate 74. Further, in the exposing stage, because the distance between a reflector and the work W is different, two photometers 77 are provided to control a light source so that the product of light quantities is always the same even the locations of the works are different.
There is provided a cooling housing for cooling a surface of a work W, next to the exposing stage. There are placed a cooling apparatus 79, a cooling fan and others in the cooling housing. A light source housing is provided next to the cooling housing. There are a light source device 78, a flyeye lens 78a, a reflector 78b and others inside the light source housing. Light from the light source device 78 irradiates a curved-reflector 78e for reflecting light in a direction perpendicular to the work W at the upper part of the light source housing.
It should be noted that the reasons for providing the cooling housing between the exposing stage and the light source housing are that the exposing stage needs to be separated apart from the light source by a predetermined distance on the requirement of irradiating the work with vertical light and that the surface of the work, the light source device and others need to be cooled.
However, there exist the following problems in the above-described exposing apparatus.
(1) With respect to the exposing apparatus-alignment apparatus separating type, spaces for the alignment apparatus and stock-unit are needed. Further, transferring the aligned work and mask film with the stock-unit causes dusts attached on the mask film and the work. Furthermore, positional deviation of the work and mask film occurs during the transfer of the aligned work and mask film.
(2) With respect to the exposing apparatus comprising image-taking means in the alignment stage, since the image-taking means is provided under the work, a process of forming holes at predetermined positions of the work is required. Therefore, working steps are increased and the apparatus for forming holes is needed. Further, if the hole is small, an irradiation beam does not pass through, and if it is large, it is inconvenient for designing circuits. Since the holes are formed with a drill, burr occurs, which scatters irradiation light. Due to this, the locating mark of the mask film cannot be read with the image-taking means, and the alignment process is failed.
(3) In the structure of the exposing apparatus, there is a process of opening and closing the upper and lower frame plates in the alignment stage (in FIG. 15, an exposing apparatus transferring position). Closing and opening the upper and lower frames takes time, which lowers the processability of works.
(4) With respect to the exposing apparatus comprising the alignment table, since the upper transparent frame plate provided with the mask film is opened and closed around the one side thereof as the rotatable support section, the prealignment cannot be performed. The position of the locating mark of the work to be mounted on the lower frame plate is hardly aligned with the position of the locating mark of the mask film, and the alignment process with the image-taking means may not be performed, depending upon the placement of the work.
(5) With respect to the exposing apparatus comprising the alignment stage, after the work on the lower frame plate is aligned on the alignment table, the lower frame plate and the upper transparent frame plate are combined to hold the work and the mask film. However, when the work and the mask film are vacuum-sucked between the upper and lower frames, positional deviation often occurs, and the alignment process needs to be repeated, which makes the work exposing process longer.
(6) The light source device of the exposing apparatus cannot irradiate the surface of the work with light unless the lamp is placed apart from the surface of the work by a predetermined distance; however, with the placement of the cooling stage between the exposing stage and the light source device, the exposing apparatus would be large.
Further, the lamp and the reflector comprise a coherent film, a vapor-deposited film and others in order to emit light in a predetermined direction. When the cooling housing and the light source housing are placed in the different locations, heat from the lamp and humidity are not adequately removed. This causes the coherent film and the vapor-deposited film coming off from the lamp and the reflector.
(7) In the case of exposing the work in the exposing stage, the light source is controlled to make the product of light quantities always the same because the distance from the light source is different. If possible, it is preferable to fix the distance between the work and the light source. The apparatus which employs this structure is expected.
The present invention has been achieved to solve the above-stated problems. It is an object of the present invention to provide an exposing apparatus with mask alignment system and a method of aligning, exposing and transferring a work, which do not occupy a large space and which accurately align the work with the mask film, and which do not require the process of closing and opening the upper and lower frames in the alignment stage, and which do not cause the positional deviation of the work and mask film after aligned, and which minimize the causes of the deterioration of the coherent film, e.g., humidity and heat from the light, and which irradiate the work in the exposing stage with light without making the size of the apparatus larger.